As a vehicle decelerates to a stop, the friction in the braking system (e.g., between the brake pads and discs) increases as the brake pressure applied to the wheels of the vehicle increases, and thus, the speed of the vehicle decreases. It has been identified that in addition, due to the dynamic characteristics of the forces acting within the brake disc/brake pad arrangement, as the vehicle slows down, at low speeds, and particularly at lower braking pressures the braking effect increases sharply shortly before the vehicle comes to a standstill. As this happens, the friction in the brakes will become sufficient to terminate rotation of the brake pads (and hence the wheels) at a time when the vehicle still has some, albeit limited, forward movement (i.e., there becomes a point at which the brake pad “grabs” the brake disc prior to the vehicle being at a complete standstill). The extent to which this will occur, and the speed and pressures at which it will occur, will be a characteristic of the brake system and will be dependent upon factors including, for example, brake disc and pad materials, sizes, and vehicle mass.
For a vehicle being decelerated to a stop whilst traversing a deformable, low-mu surface, such as, for example, sand, gravel, mud, or wet grass, the effect of the disc “grabbing” the pad and terminating wheel rotation may cause the wheels of the vehicle to skid a short distance and dig into the material forming the surface (e.g., sand, gravel, mud, etc.) as the vehicle comes to a standstill because the surface cannot withstand the friction between the wheels and the surface material required to stop the vehicle. As a result, the material forming the surface (e.g., sand, mud, gravel, etc.) may build up in front of the vehicle wheels, making it more difficult to subsequently pull away in a composed manner (i.e., because the vehicle must overcome the build-up of material before progressing in a desired manner).
Similarly, when a vehicle is being decelerated to a stop whilst traveling a high-mu surface (e.g., pavement), and both the brake pressure and speed are below certain particular amounts, the friction in the brake system in the final portion of a braking event may result in the vehicle coming to an abrupt stop without skidding (i.e., the friction increases to a point at which the pads “grab” the disc). In other words, rather that the vehicle speed gradually reducing to zero, it will reduce to a particular speed and then the friction in the braking system, combined with the high friction between the wheels and the high-mu surface, will cause the vehicle to abruptly stop. As such, rather than slowing to a stop in a smooth, composed manner, the front end of the vehicle may dip or dive downward relative to the back end of the vehicle, resulting in the stopping of the vehicle in an abrupt, uncomposed manner that may be uncomfortable to the passengers in the vehicle.
Accordingly, it is an aim of the present invention to address, for example, the disadvantages identified above.